The problem with shaving long growth your first time is that if you get the angle wrong, which happens frequently at first, you are more likely to razor burn yourself. I believe you are best off to shave your first time with short growth; just a whisper of stubble.

In fact, I recommend that you shave your first time with NO growth, after a full shave with your previous method of shaving. Learn safe blade angle and pressure and movement and hand grips first, without worrying about how well you are shaving. Then, next time you shave, you will bring more confidence with you.